As disclosed in U.S. Pat. No. 6,543,915, a lamp bulb is disposed inside a lamp holder. The lamp holder has two pivot rods bilaterally disposed at the bottom thereof and respectively positioned in two notches of a rotary carrier. Two upright rods are disposed adjacent to the notches, respectively. The upright rods are screwed onto a pressing plate such that the lamp holder can be pivotally connected to the rotary carrier for adjusting the lighting angle of the lamp bulb.
The pivot rods are bilaterally disposed on the outside bottom of the lamp holder so the notches must provide sufficient space for holding the pivot rods. As a result, the dimension of the recessed lamp structure is increased, and much more components are also required. Consequently, the integral efficiency is affected and the product cannot be minimized.